With increasing life expectancy, upper extremity (UE) function becomes more and more important in boys with Duchenne muscular dystrophy (DMD). Knowledge of UE function in these children is, however, limited. The aim of this study was to gain insight into the changing patterns of UE function during the course of DMD. A Web-based questionnaire on UE function, covering all domains of the International Classification of Functioning Disability and Health, was distributed worldwide. Primary domains of the questionnaire were: participant characteristics, UE pain and stiffness, UE activities, and social participation. Data were described per disease stage and analyzed using descriptive analysis. A total of 213 boys/men with DMD (1-35 years) were included in this study. UE pain, stiffness, and activity limitations increased with disease stage. UE activity limitations already occurred in the early ambulatory stage. Compared to the healthy population, social participation was restricted in DMD patients and about 70% of the respondents experienced UE limitations when performing social activities. Despite the existence of UE impairments, only 9% of the respondents used supportive aids. Functional capacities and activities of the UE are limited already in the early ambulatory stage of patients with DMD affecting their social participation. Therefore, clinicians should pay attention to UE limitations before DMD patients lose their capacity to walk. Effective and adequate aids as well as attention for pain and stiffness in the therapeutic management could help to reduce UE activity limitations and related restrictions in social participation.